The present invention relates to an improvement in a walk behind self-propelled crawler snowplow.
In recent years, an auger-type self-propelled snowplow maneuverable by a human operator walking behind the snowplow has been used extensively as it can reduce labor in a snow removing work in a relatively small area. One example of such conventional walk behind self-propelling snowplow is disclosed in Japanese Patent Laid-open Publication No. (Sho) 63-223207.
The disclosed snowplow is equipped with an auger and an impeller disposed on a front portion of a vehicle body, an engine disposed on a central portion of the vehicle body, left and right handlebars connected to a rear portion of the vehicle body, and left and right crawler belts disposed on left and right sides of the vehicle body.
The engine drives the auger and impeller via an auger clutch. The engine also drives the crawler belts via a mechanical propelling clutch, a transmission, and left and right driving sprockets. Thus, a snowplow mechanism including the auger and impeller and a propelling mechanism including the crawler belts are both driven by a single prime motor comprised of the engine.
In general, in the walk behind self-propelled snowplow, power from the single engine is distributed to the snowplow mechanism and the propelling mechanism at the ratio of about 9:1. More specifically, the power ratio divided between the auger, impeller and propeller mechanism is about 2:7:1.
In spite of its small power consumption, the propelling mechanism of the conventional snowplow requires a power transmission mechanism which is large in size and complicated in construction as it includes the above-mentioned mechanical propelling clutch and transmission. Due to such large and complicated propelling power transmission system, the clutch onoff operation, speed change operation and vehicle turning operation are tedious and require a relatively large muscular effort.
Furthermore, there has been a keen demand for a snowplow with good weight balance leading to improved maneuverability of the snowplow. To this end, the arrangement of a power source including a propelling power transmission system forms a major requirement in designing a walk behind self-propelled crawler snowplow.
It is accordingly an object of the present invention to provide a walk behind self-propelled crawler snowplow with good weight balance and improved maneuverability.
To achieve the foregoing object, there is provided according to the present invention a walk behind self-propelled crawler snowplow comprising: a vehicle body; a snowplow mechanism disposed on a front portion of the vehicle body, the snowplow mechanism including an auger; an engine disposed on a longitudinal central portion of the vehicle body for driving the snowplow mechanism; a left crawler belt and a right crawler belt disposed on a left side and a right side, respectively, of the vehicle body; and left and right electric motors disposed on a rear portion of the vehicle body for driving the left and right crawler belts, respectively.
Since the snowplow mechanism and the electric motors are disposed on opposite longitudinal end portions of the vehicle body with the engine disposed on a longitudinal central portion of the vehicle body, the crawler snowplow has a good weight balance such that the load or weight of the vehicle body is evenly born by the left and right crawler belts disposed on opposite sides of the vehicle body. This improves the maneuverability of the crawler snowplow.
Furthermore, the electric motors disposed on the left and right sides, respectively, of the rear portion of the vehicle body act as a counterbalance to the snowplow mechanism disposed on the front portion of the vehicle body. With this counterbalancing, the crawler snowplow can easily ride across and wedge through snow, thus showing a good breakthrough performance on the snow.
Because the snowplow mechanism, which shears about 90% of the overall necessary power of the crawler snowplow, and the propelling mechanism (crawler belts ), which shears about 10% of the overall necessary power, are driven separately by different power sources, the crawler snowplow can exhibit its driving performance regardless of the condition of load exerted on the snowplow mechanism. In addition, since the left and right electric motors are separately controllable, electrically controlling of the rotational speed of the individual electric motors enables smooth and easy speed change and turning operations of the crawler snowplow.
In one preferred from of the present invention, the walk behind self-propelled crawler snowplow further includes a pair of left and right operation handlebars extending from the rear portion of the vehicle body obliquely upward in a rearward direction of the crawler snowplow, a control unit mounted to the operation handlebars at a higher level than the crawler belts for controlling operation of the electric motors, and a battery mounted to the operation handlebars at a higher level than the crawler belts for supplying electric power to the electric motors.
Since the control unit and battery are arranged more backward than the vehicle body, a fine adjustment of the longitudinal weight balance of the crawler snowplow becomes possible, which insures an improved breakthrough performance of the crawler snowplow. The control unit and battery located at higher levels than the crawler belts are protected from damage or deterioration with snow.
Preferably, the control unit and the battery are disposed in a vertical space defined between the left and right handlebars. The control unit is preferably disposed above the battery.
It is preferable that the vehicle body is composed of a propelling frame supporting thereon the left and right crawler belts and the left and right electric motors, a vehicle frame pivotally connected at a rear end portion thereof to a rear portion of the propelling frame and supporting thereon the snowplow mechanism and the engine, and a frame lift mechanism connected to the propelling frame and the vehicle frame and operable to move a front end portion of the vehicle frame up and down relative to the propelling frame. The frame lift mechanism may be a cylinder actuator having a cylinder tube pivotally connected to the propelling frame and a reciprocating piston rod pivotally connected to the vehicle frame.
Preferably, the left crawler belt is trained around a left driving wheel and a left idler wheel, the right crawler belt is trained around a right driving wheel and a right idler wheel, the left and right idler wheels are fixed on opposite ends of a front axle rotatably supported on a front end portion of the propelling frame, the left electric motor is a geared motor mounted to a rear end portion of the propelling frame on the left side of the vehicle body and having an output shaft on which the left driving wheel is fixed, and the right electric motor is a geared motor mounted to the rear end portion of the propelling frame on the right side of the vehicle body and having an output shaft on which the right driving wheel is fixed. By using the geared motors, a propelling power transmission system for transmitting power from the motors to the respective crawler belts is considerably small in construction and contributes downsizing of the snowplow.
It is preferable that the front end portion of the propelling frame has a horizontal slot extending in the longitudinal direction of the vehicle body and slidably receiving therein a longitudinal portion of the front axle, and a tension adjustment device is associated with the propelling frame and operative to move the front axle along the horizontal slot to thereby adjust a tension in the crawler belts.
The above and other objects, features and advantages of the present invention will become manifest to those versed in the art upon making reference to the following description and accompanying sheets of drawings in which a certain preferred structural embodiment incorporating the principle of the invention is shown by way of illustrative example.